Inferior quality products used in the cabin - Mercedes Benz C Class

Both front headrests rattle. We purchased a brand new model in 2016 and noticed that the cabin was very noisy this year. Took the vehicle it back to our closest dealership for a check up and they told us that the front headrests were damaged. The plastic parts in the headrests are of an inferior quality and we now have to pay R4000.00 per headrest. The dealership was told by Mercedes SA that the customer broke their headrests and they will not replace it. Why would a customer do this to their own vehicle??? Shocking customer service from such a large vehicle brand.